1. Field of the Invention
The present invention relates to a device for projecting a pattern having a light area and a dark area on an image sensor and detecting the position of said pattern on said image sensor, and more particularly to such position detecting device adapted for use in surveying instruments such as a theodolite or a level for detecting the inclination to a reference plane or in measuring instruments such as a collimater for detecting the angle thereof.
2. Description of the Prior Art
In a known device of this sort in which the pattern position is detected from the output signals of an image sensor composed of a linear array of plural charge-accumulating photoelectric converting elements, it is necessary to reduce the length of each element for improving the precision of position measurement since the output signals from such image sensor are digitized by the elements. However the length of each element is physically limited, and the resolving power of such device is therefore determined by the length of each element.